Introduction: Assessment of ischemic and bleeding risk is critical for the management of elderly patients with acute coronary syndromes, but it has been little studied. Objective: This study aims to assess the applicability of the GRACE and CRUSADE scores in patients aged >= 80 years with non-ST-elevation acute coronary syndrome (NSTE-ACS), and to identify the main predictors of in-hospital mortality and major bleeding in this population. Methods: We analyzed 544 patients aged >= 80 years with NSTE-ACS included in the Portuguese Registry on Acute Coronary Syndromes and identified the predictors of in-hospital mortality and major bleeding during hospitalization. Prediction models were created for these endpoints, then compared with the GRACE and CRUSADE scores, and their applicability to the study population was assessed. Results: Use of coronary angiography was associated with reduced risk of in-hospital mortality, without increasing risk of major bleeding (OR 0.2, 95% CI 0.006-0.49, p=0.001). Major bleeding was an independent predictor of in-hospital mortality (OR 10.9, 95% Cl 2.36-50.74, p=0.002), and was associated with comorbidities and pharmacological therapy during hospitalization. The GRACE score showed good diagnostic accuracy for in-hospital mortality (AUC 0.75, 95% CI 0.63-0.87, p<0.001), but the CRUSADE score had weak discriminatory capacity for major bleeding (AUC 0.51, 95% Cl 0.30-0.63, p=0.942), unlike our prediction model (AUC 0.68, 95% CI 0.52-0.84, p=0032). Conclusions: The GRACE score is suitable for risk assessment in octogenarians with NSTE-ACS, but the CRUSADE score is inadequate, and new scores are required to assess bleeding risk in this age-group. (C) 2013 Sociedade Portuguesa de Cardiologia. Published by Elsevier Espana, S.L.U. All rights reserved.